1. Field of the Invention
The present invention relates to a non-ferrous spacer for welded wire reinforcement in concrete that attaches at any one perpendicular welded wire intersection of any wire diameter and properly positions the welded wire reinforcement or helical (spiral) reinforcement cage in the body of the form by spacing the reinforcement a specified distance from the outside and/or inside form and/or from other welded wire reinforcements or reinforcement cages.
2. Description of the Related Art
In the manufacture of reinforced concrete structures, specifically reinforced concrete pipe, slabs, walls, and other reinforced concrete products, it is important that the welded wire reinforcement or helical (spiral) reinforcement cage, both made from steel wire with perpendicular welded intersections, is properly positioned within the body of the form prior to the introduction of concrete. Improper positioning of the steel reinforcement will reduce the structural integrity of the reinforced concrete product and may lead to structural failure when placed under a load.
Prior art spacers are known that are manufactured from metal wire and attach at or adjacent to a perpendicular welded wire intersection. Examples of such spacers are disclosed in U.S. Pat. Nos. 3,722,164 to Schmidgall, 4,452,026 to Tolliver, 4,920,724 to Leach et al. and 4,939,883 to Swenson. Within the past decade some United States federal and state agencies have issued specifications that do not allow metal to come in contact with the inside or outside concrete forms. Their belief is that the portion of the metal spacer that touches the inside or outside form is exposed to the atmosphere and will gradually oxidize. As the metal spacer oxidizes, it creates a void which then provides a conduit for moisture to eventually reach the welded wire reinforcement. The welded wire reinforcement will then begin to oxidize and, over time, will result in structural failure of the reinforced concrete product.
There are also known prior art spacers that are manufactured from non-ferrous material. U.S. Pat. Nos. 5,347,787 and 6,385,938 to Gavin and 7,451,579 to Azarin disclose variations of a plastic molded wheel-type spacer that is designed primarily for reinforcement rods or bars (also referred to as rebar). U.S. Pat. Nos. 6,758,021 and 6,910,309 to Trangsrud disclose variations of the same plastic molded clip-on type pyramid spacer that consists of two intersecting triangular planes that come to a point. The pyramid spacer also has two clips at the end of the base to attach to welded wire reinforcement at a perpendicular welded intersection. This pyramid-type spacer has three disadvantages that impair its usefulness:
(1) In many cases the clip-on connector does not compensate for the various wire diameters resulting in the pyramid spacer rocking back and forth at the welded intersection. When the concrete is introduced into the form, this rocking motion can cause a void from the outside and/or inside form which will require additional labor to patch the void after the concrete cures.
(2) The clip-on connectors allow the pyramid spacer to twist or turn at the welded intersection. This twisting or turning allows an inconsistent spacing distance between the welded intersection and the form. It is imperative to have a spacer that will remain aligned to the welded intersection to maintain the reinforcement at a consistent distance from the form.
(3) In severe cases such as cage twist caused by the equipment during the manufacturing process, the clip-on connection can fail by twisting off which would result in the pyramid spacer disengaging from the welded intersection resulting in a reinforcement cage moving from its proper position and negatively affecting the structural integrity of the reinforced concrete product.